The most common misconception: “We are married, so everything belongs to us jointly.” That is not true. The owner is whoever is on the land register. If both names are there – usually half each – the flat belongs to both. If only one is there, it belongs to that person alone, even if the other has paid the instalments for years.
What marriage regulates is equalisation of accrued gains (Zugewinnausgleich): whoever built up more wealth during the marriage pays half the difference to the other on divorce – as a cash payment, not as a share of the property. A flat that belongs to one partner alone is therefore not split, but its rise in value since the wedding goes into the calculation. What was there before the marriage, or was gifted and inherited, counts as starting assets and is not equalised.
Two dates, one value: for equalisation of gains the value at service of the divorce petition counts; for dividing jointly owned property, the value at the time of agreement. A valuation both of you accept saves surveyor’s fees and many weeks of argument here.